All three Catholic dioceses in Tennessee and Tennessee Right to Life, an organization dedicated to ending abortion, have publicly opposed the so-called "heartbeat" bill. They say the bill will face certain legal challenges, embroiling the state in expensive litigation in which it is unlikely to prevail.

The measure would ban most abortions at the point a fetal heartbeat is detected — typically at six weeks of pregnancy — and make it a felony for doctors to perform them. There is no exception for rape or incest.

Some of the state's staunchest anti-abortion Republicans are at odds with their former allies, the anti-abortion organizations that have helped usher in significant abortion restrictions during the past decade.

Tennessee Right to Life spearheaded a years-long effort to amend the state's constitution giving lawmakers more authority to restrict abortion. The Catholic Church has consistently lobbied for anti-abortion legislation.

"I've got no problem with Tennessee Right to Life," said Rep. Micah Van Huss, R-Jonesborough, the chief sponsor of the heartbeat bill. "I appreciate the work they've done saving our unborn. I would ask them about why they are not backing (the bill)."

But in Van Huss' east Tennessee district, residents got robocalls criticizing Tennessee Right to Life.

Tennessee Right to Life President Brian Harris said Van Huss' measure could "gravely harm this state's existing pro-life public policies and grassroots gains."

Micah Van Huss(Photo: Jed DeKalb)

"We are grateful to live in a strongly pro-life state," he said. "At the same time, Tennessee Right to Life is going to continue to express our sincere concern at the bill's constitutional challenge and the potential consequences for existing pro-life laws that are saving lives and helping women and girls in our state."

A split over strategy

The rift exposes the divergent strategies that have emerged between certain abortion opponents and some Republicans — a pragmatic and methodical approach to eroding abortion access versus a more direct attack on abortion that will face legal challenges.

A longstanding lawsuit challenging a 2015 law requiring a 48-hour mandatory waiting period before a woman can obtain an abortion goes to trial in September.

The Tennessee American Civil Liberties Union and Planned Parenthood of Tennessee and Northern Mississippi said they will file suit should the heartbeat bill be signed into law. Gov. Bill Lee has said he supports the measure.

The anti-abortion groups also worry that enacting the law could have unintended consequences.

Any court review of the heartbeat bill could expand to include other abortion restrictions already in place in Tennessee. A judge could examine all of Tennessee's abortion restrictions to determine whether they cumulatively imposed an "undue burden" on women seeking an abortion, a standard set by the Supreme Court. That could place other abortion restrictions at risk.

Van Huss, however, has said those concerns are secondary to his goal of ending abortion. Speaker Glen Casada, R-Franklin, has thrown his political weight behind the bill, calling himself a "big supporter of Rep. Van Huss and the heartbeat bill."

"We cannot continue to allow the slaughter of the unborn while we hope for better circumstances," Van Huss said.

Last-minute consensus from GOP caucus

On Wednesday, the day before the House voted, Republican lawmakers submitted several amendments to temper Van Huss' efforts and incorporate anti-abortion advocates' concerns.

The last-minute filings led to Thursday's early morning huddle of the GOP caucus before the House session as confused lawmakers tried to make sense of the competing measures, minutes before they stepped inside for a public debate.

"When we get on the floor today, this is going to be one of the most publicized votes that we as a caucus carry this year," said Rep. Kevin Vaughan, R-Collierville.

"For us to be out there looking at each other with a blank look on our face and then trying to figure out which (amendments) are good and which ones are bad, I think will put all of us to where we look less than professional and look like we don't really have our act together."

Conscious their discussion was being broadcast, Van Huss stepped back from the room's microphone, saying: "I'm not on the microphone because there's people out there."

By the time the bill came up for a vote, most Republicans had reached consensus on an amendment offered by Rep. Matthew Hill that made two major changes to Van Huss' original proposal.

The first was language that made clear if the bill was halted or overturned in court, or if the state's attorney general declined to defend it, a pre-existing Tennessee law banning abortions after 20 weeks of pregnancy would remain.

The second significant change was adding an exception to the ban on abortions after a fetal heartbeat is detected for pregnancies that are "not viable."

The bill already includes an exception to "prevent the death of the pregnant woman or to prevent serious risk of substantial and irreversible impairment of a major bodily function or for any reason relating to her mental health."

Efforts by a Democratic lawmaker to include an exception for pregnancies that are a result of rape or incest failed Thursday.

A similar heartbeat measure lags behind in the Senate, which has not held a committee hearing to examine it.

'Caught in a narrative created by their opponents'

Abortion rights advocates, meanwhile, say they are already preparing for a legal battle.

"The House and Senate may disagree on details and strategy, but their end game is the same," said Ashley Coffield, president and CEO of Planned Parenthood of Tennessee and North Mississippi.

"Politicians in both chambers want to end abortion rights in Tennessee with no exceptions," she said.

Some Democrats and abortion rights advocates are also at odds over strategy.

In committee hearings, Democrats made the lack of a rape and incest exception the focus of their opposition — a point Coffield said fails to emphasize abortion rights advocates' message that abortion is a "safe and common medical procedure."

"Some of the Democrats in the legislature who support the right to abortion in Tennessee seem caught in a narrative created by their opponents," Coffield said. "They respond to attacks on every woman's fundamental right to personal autonomy by citing extreme hypothetical situations. We're counting on Democrats to support high-quality medical care, not to play political games with extremists."